This application relates generally to an electrochemical cell or battery, and more specifically relates to a flat, thin, electrochemical cell utilizing a picture frame feature and its method of manufacture, including printing methods. Even more specifically, this invention relates to a thin printable cell comprising two or more electrodes, a separator, electrolyte, and a cell frame between two laminated film layers, and its method of manufacture.
For the past one hundred years or so, scientists have been making Carbon/Zinc portable power sources for various applications. In the early days of portable power, these power sources were very large compared to today's standards. For example, the very popular “Igniter Cell” made by Eveready was about 3″ diameter and about 9″ tall and was used in many applications such as radios, buzzers, Xmas lighting, etc. These large cells, as well as some smaller versions, such as the famous Eveready #6 (about 2″ dia.×6″ tall) and the smallest unit cell of the day, the #950 (D size), were commonly made into battery packs with voltages exceeding 40 volts in some applications. These were similar in size, and even larger, than today's car batteries, for uses in lighting devices, radios and car ignition systems. In the mid 1900's, with the advent of advanced electronics such as the transistor, the electrical requirements for portable power sources were drastically reduced. Consequently, cell sizes could also be reduced to include C's, AA's, and AAA's, and even small button cells. This power reduction has continued into the twenty-first century, where applications such as smart labels, smart credit cards, sensors, data loggers, novelty devices such as greeting cards and badges, etc., now require a maximum current of several milliamperes, with many applications requiring as little as a few microamperes at about 1.5-3.0 volts. These applications also have the requirement that the power sources be flat and very thin to maintain their low profiles and portability.
In the past twenty-five years, various approaches for making thin, flat cells and batteries were attempted by numerous scientists and corporations. These include the widely known instant film battery pack developed by Polaroid. This battery pack was used in each package of Polaroid instant film. This allowed Polaroid to have a fresh battery in the camera each time the user placed a new pack of film in the camera. This high cost battery with multiple layers and a metal foil laminate package is a high voltage, high current battery, capable of igniting flash bulbs and powering motors, for example, and is not a realistic competitor of the new thin low cost batteries that are needed. In addition to Polaroid, others have tried to develop thin batteries in various electrochemical systems.
Co-pending U.S. application Ser. Nos. 11/110,202 filed on Apr. 20, 2005 and 11/378,520 filed on Mar. 17, 2006 incorporated herein by reference, discuss new designs and methods of manufacture of a flat cell and battery.
With the growing market needs for low cost, low capacity thin flat cells, it would be beneficial to produce a thin, flat, printable flexible cell that is versatile and inexpensive to mass-produce. Printable, disposable thin cells that are well suited for low-power and high-production volume applications would be useful, especially if they offer adequate voltage, sufficient capacity, and low-cost solutions. Conventional low-profile batteries typically have few of these attributes, if any.
Furthermore, in recent years there has been a growing need for various electronic devices, such as active RFID tags, sensors with RFID tags, skin patches that deliver iontophoretic or other electrical functionality, etc. These various electronic devices can have various electrical loading characteristics. Thus, it can be beneficial to provide thin flat power sources that can reliably deliver relatively higher currents. In one example, the thin flat power sources can be separately manufactured and later electrically coupled to various electronic devices. In another example, the manufacture of the thin flat power sources can be integrated with the manufacture of the desired circuitry of electrical components to power the components.